There are no exactly "matching" numbers. However, the engine serial number and vehicle serial number should be correct for 1951. Also, the date casting codes for the head and block should be relatively close to each other (and should be in 1951 or late 1950).

Is it a Canadian Chevrolet truck or a USA Chevrolet truck?

Post the codes that the seller says are "matching".

locations of engine codes

1951 serial numbers

more examples of serial number locations